inessential.com: Anatomy of a feature
Good description of thinking thru feature implementation. error handling, sync failures, user feedback, etc
Anatomy of a feature: http://bit.ly/3R0Ws Great step-by-step guide on how an idea gets turned into software. [from http://twitter.com/dhinchcliffe/statuses/2954188093]
NetNewsWire's developer Brent Simmons describes all the UI decisions he had to go through before adding the Instapaper functionality to the feed reader's latest beta : "It’s not enough just to write the basic functionality and add a menu item that runs it. Even a feature as simple as this one requires some up-front thinking, some design."
A great post on just how much it really takes to "add this simple feature that does XXX" to software.jQueryGlobe | jQuery Plugin - Feature List